/*
 * Copyright (C) 2007 Esmertec AG.
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.mms.pdu;

import java.io.UnsupportedEncodingException;
import java.util.HashMap;

public class CharacterSets {
	/**
	 * IANA assigned MIB enum numbers.
	 * 
	 * From wap-230-wsp-20010705-a.pdf Any-charset = <Octet 128> Equivalent to
	 * the special RFC2616 charset value "*"
	 */
	public static final int ANY_CHARSET = 0x00;
	public static final int US_ASCII = 0x03;
	public static final int ISO_8859_1 = 0x04;
	public static final int ISO_8859_2 = 0x05;
	public static final int ISO_8859_3 = 0x06;
	public static final int ISO_8859_4 = 0x07;
	public static final int ISO_8859_5 = 0x08;
	public static final int ISO_8859_6 = 0x09;
	public static final int ISO_8859_7 = 0x0A;
	public static final int ISO_8859_8 = 0x0B;
	public static final int ISO_8859_9 = 0x0C;
	public static final int SHIFT_JIS = 0x11;
	public static final int UTF_8 = 0x6A;
	public static final int BIG5 = 0x07EA;
	public static final int UCS2 = 0x03E8;
	public static final int UTF_16 = 0x03F7;

	/**
	 * If the encoding of given data is unsupported, use UTF_8 to decode it.
	 */
	public static final int DEFAULT_CHARSET = UTF_8;

	/**
	 * Array of MIB enum numbers.
	 */
	private static final int[] MIBENUM_NUMBERS = { ANY_CHARSET, US_ASCII, ISO_8859_1, ISO_8859_2, ISO_8859_3,
			ISO_8859_4, ISO_8859_5, ISO_8859_6, ISO_8859_7, ISO_8859_8, ISO_8859_9, SHIFT_JIS, UTF_8, BIG5, UCS2,
			UTF_16, };

	/**
	 * The Well-known-charset Mime name.
	 */
	public static final String MIMENAME_ANY_CHARSET = "*";
	public static final String MIMENAME_US_ASCII = "us-ascii";
	public static final String MIMENAME_ISO_8859_1 = "iso-8859-1";
	public static final String MIMENAME_ISO_8859_2 = "iso-8859-2";
	public static final String MIMENAME_ISO_8859_3 = "iso-8859-3";
	public static final String MIMENAME_ISO_8859_4 = "iso-8859-4";
	public static final String MIMENAME_ISO_8859_5 = "iso-8859-5";
	public static final String MIMENAME_ISO_8859_6 = "iso-8859-6";
	public static final String MIMENAME_ISO_8859_7 = "iso-8859-7";
	public static final String MIMENAME_ISO_8859_8 = "iso-8859-8";
	public static final String MIMENAME_ISO_8859_9 = "iso-8859-9";
	public static final String MIMENAME_SHIFT_JIS = "shift_JIS";
	public static final String MIMENAME_UTF_8 = "utf-8";
	public static final String MIMENAME_BIG5 = "big5";
	public static final String MIMENAME_UCS2 = "iso-10646-ucs-2";
	public static final String MIMENAME_UTF_16 = "utf-16";

	public static final String DEFAULT_CHARSET_NAME = MIMENAME_UTF_8;

	/**
	 * Array of the names of character sets.
	 */
	private static final String[] MIME_NAMES = { MIMENAME_ANY_CHARSET, MIMENAME_US_ASCII, MIMENAME_ISO_8859_1,
			MIMENAME_ISO_8859_2, MIMENAME_ISO_8859_3, MIMENAME_ISO_8859_4, MIMENAME_ISO_8859_5, MIMENAME_ISO_8859_6,
			MIMENAME_ISO_8859_7, MIMENAME_ISO_8859_8, MIMENAME_ISO_8859_9, MIMENAME_SHIFT_JIS, MIMENAME_UTF_8,
			MIMENAME_BIG5, MIMENAME_UCS2, MIMENAME_UTF_16, };

	private static final HashMap<Integer, String> MIBENUM_TO_NAME_MAP;
	private static final HashMap<String, Integer> NAME_TO_MIBENUM_MAP;

	static {
		// Create the HashMaps.
		MIBENUM_TO_NAME_MAP = new HashMap<Integer, String>();
		NAME_TO_MIBENUM_MAP = new HashMap<String, Integer>();
		assert (MIBENUM_NUMBERS.length == MIME_NAMES.length);
		int count = MIBENUM_NUMBERS.length - 1;
		for (int i = 0; i <= count; i++) {
			MIBENUM_TO_NAME_MAP.put(MIBENUM_NUMBERS[i], MIME_NAMES[i]);
			NAME_TO_MIBENUM_MAP.put(MIME_NAMES[i], MIBENUM_NUMBERS[i]);
		}
	}

	private CharacterSets() {
	} // Non-instantiatable

	/**
	 * Map an MIBEnum number to the name of the charset which this number is
	 * assigned to by IANA.
	 * 
	 * @param mibEnumValue
	 *            An IANA assigned MIBEnum number.
	 * @return The name string of the charset.
	 * @throws UnsupportedEncodingException
	 */
	public static String getMimeName(int mibEnumValue) throws UnsupportedEncodingException {
		String name = MIBENUM_TO_NAME_MAP.get(mibEnumValue);
		if (name == null) {
			throw new UnsupportedEncodingException();
		}
		return name;
	}

	/**
	 * Map a well-known charset name to its assigned MIBEnum number.
	 * 
	 * @param mimeName
	 *            The charset name.
	 * @return The MIBEnum number assigned by IANA for this charset.
	 * @throws UnsupportedEncodingException
	 */
	public static int getMibEnumValue(String mimeName) throws UnsupportedEncodingException {
		if (null == mimeName) {
			return -1;
		}

		Integer mibEnumValue = NAME_TO_MIBENUM_MAP.get(mimeName);
		if (mibEnumValue == null) {
			throw new UnsupportedEncodingException();
		}
		return mibEnumValue;
	}
}
